Mechano-chemical polishing method for GaAs wafer

Abstract

A method of performing mechano-chemical polishing serving as a primary polishing operation for a GaAs wafer, by using a mechano-chemical polishing solution containing dichloroisocyanuric acid, sodium tripolyphosphate, sodium sulfate, sodium carbonate, and colloidal silica as components except for water, includes the steps of: mounting the wafer on a mechano-chemical polishing apparatus; performing first-stage polishing by supplying the polishing apparatus with the polishing solution having a first composition in which 20-31 mass % of sodium tripolyphosphate is contained in the components except for water; and subsequently performing second-stage polishing by supplying the polishing apparatus with the polishing solution having a second composition in which 13-19 mass % of sodium tripolyphosphate is contained in the components except for water.

1 . A method of performing mechano-chemical polishing serving as a primary polishing operation for a GaAs wafer, by using a mechano-chemical polishing solution containing dichloroisocyanuric acid, sodium tripolyphosphate, sodium sulfate, sodium carbonate, and colloidal silica as components except for water, comprising the steps of:
 mounting said wafer on a mechano-chemical polishing apparatus;   performing first-stage polishing by supplying-said polishing apparatus with a polishing solution having a first composition in which 20-31 mass % sodium tripolyphosphate is contained in said components except for water; and   subsequently performing second-stage polishing by supplying said polishing apparatus with another polishing solution having a second composition in which 13-19 mass % sodium tripolyphosphate is contained in said components except for water.   
   
   
       2 . The method of mechano-chemical polishing for the GaAs wafer according to  claim 1 , wherein said mechano-chemical polishing solution contains 40-50 mass % colloidal silica in the components except for water. 
   
   
       3 . The method of mechano-chemical polishing for the GaAs wafer according to  claim 1 , wherein, in order to eject the polishing solution having said first composition from said polishing apparatus after said first-stage polishing, said polishing apparatus is driven for a cleaning period of 5-60 seconds after termination of supply of the polishing solution having said first composition, and said second-stage polishing is subsequently performed. 
   
   
       4 . The method of mechano-chemical polishing for the GaAs wafer according to  claim 3 , wherein water or water containing the colloidal silica is supplied to said polishing apparatus during said cleaning period.